bits/libc-header-start.h

   1 /* Handle feature test macros at the start of a header.
   2    Copyright (C) 2016-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 /* This header is internal to glibc and should not be included outside
  20    of glibc headers.  Headers including it must define
  21    __GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION first.  This header
  22    cannot have multiple include guards because ISO C feature test
  23    macros depend on the definition of the macro when an affected
  24    header is included, not when the first system header is
  25    included.  */
  26
  27 #ifndef __GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION
  28 # error "Never include <bits/libc-header-start.h> directly."
  29 #endif
  30
  31 #undef __GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION
  32
  33 #include <features.h>
  34
  35 /* ISO/IEC TR 24731-2:2010 defines the __STDC_WANT_LIB_EXT2__
  36    macro.  */
  37 #undef __GLIBC_USE_LIB_EXT2
  38 #if (defined __USE_GNU                                                  \
  39      || (defined __STDC_WANT_LIB_EXT2__ && __STDC_WANT_LIB_EXT2__ > 0))
  40 # define __GLIBC_USE_LIB_EXT2 1
  41 #else
  42 # define __GLIBC_USE_LIB_EXT2 0
  43 #endif
  44
  45 /* ISO/IEC TS 18661-1:2014 defines the __STDC_WANT_IEC_60559_BFP_EXT__
  46    macro.  Most but not all symbols enabled by that macro in TS
  47    18661-1 are enabled unconditionally in C23.  In C23, the symbols in
  48    Annex F still require a new feature test macro
  49    __STDC_WANT_IEC_60559_EXT__ instead (C23 does not define
  50    __STDC_WANT_IEC_60559_BFP_EXT__), while a few features from TS
  51    18661-1 are not included in C23 (and thus should depend on
  52    __STDC_WANT_IEC_60559_BFP_EXT__ even when C23 features are
  53    enabled).
  54
  55    __GLIBC_USE (IEC_60559_BFP_EXT) controls those features from TS
  56    18661-1 not included in C23.
  57
  58    __GLIBC_USE (IEC_60559_BFP_EXT_C23) controls those features from TS
  59    18661-1 that are also included in C23 (with no feature test macro
  60    required in C23).
  61
  62    __GLIBC_USE (IEC_60559_EXT) controls those features from TS 18661-1
  63    that are included in C23 but conditional on
  64    __STDC_WANT_IEC_60559_EXT__.  (There are currently no features
  65    conditional on __STDC_WANT_IEC_60559_EXT__ that are not in TS
  66    18661-1.)  */
  67 #undef __GLIBC_USE_IEC_60559_BFP_EXT
  68 #if defined __USE_GNU || defined __STDC_WANT_IEC_60559_BFP_EXT__
  69 # define __GLIBC_USE_IEC_60559_BFP_EXT 1
  70 #else
  71 # define __GLIBC_USE_IEC_60559_BFP_EXT 0
  72 #endif
  73 #undef __GLIBC_USE_IEC_60559_BFP_EXT_C23
  74 #if __GLIBC_USE (IEC_60559_BFP_EXT) || __GLIBC_USE (ISOC23)
  75 # define __GLIBC_USE_IEC_60559_BFP_EXT_C23 1
  76 #else
  77 # define __GLIBC_USE_IEC_60559_BFP_EXT_C23 0
  78 #endif
  79 #undef __GLIBC_USE_IEC_60559_EXT
  80 #if __GLIBC_USE (IEC_60559_BFP_EXT) || defined __STDC_WANT_IEC_60559_EXT__
  81 # define __GLIBC_USE_IEC_60559_EXT 1
  82 #else
  83 # define __GLIBC_USE_IEC_60559_EXT 0
  84 #endif
  85
  86 /* ISO/IEC TS 18661-4:2015 defines the
  87    __STDC_WANT_IEC_60559_FUNCS_EXT__ macro.  Other than the reduction
  88    functions, the symbols from this TS are enabled unconditionally in
  89    C23.  */
  90 #undef __GLIBC_USE_IEC_60559_FUNCS_EXT
  91 #if defined __USE_GNU || defined __STDC_WANT_IEC_60559_FUNCS_EXT__
  92 # define __GLIBC_USE_IEC_60559_FUNCS_EXT 1
  93 #else
  94 # define __GLIBC_USE_IEC_60559_FUNCS_EXT 0
  95 #endif
  96 #undef __GLIBC_USE_IEC_60559_FUNCS_EXT_C23
  97 #if __GLIBC_USE (IEC_60559_FUNCS_EXT) || __GLIBC_USE (ISOC23)
  98 # define __GLIBC_USE_IEC_60559_FUNCS_EXT_C23 1
  99 #else
 100 # define __GLIBC_USE_IEC_60559_FUNCS_EXT_C23 0
 101 #endif
 102
 103 /* ISO/IEC TS 18661-3:2015 defines the
 104    __STDC_WANT_IEC_60559_TYPES_EXT__ macro.  */
 105 #undef __GLIBC_USE_IEC_60559_TYPES_EXT
 106 #if defined __USE_GNU || defined __STDC_WANT_IEC_60559_TYPES_EXT__
 107 # define __GLIBC_USE_IEC_60559_TYPES_EXT 1
 108 #else
 109 # define __GLIBC_USE_IEC_60559_TYPES_EXT 0
 110 #endif